A known open-type diaper includes a waistline member and a main body. The open-type diaper also includes fastening tapes to join the waistline member and the main body, and leakage prevention portions configured to prevent body discharge from leaking between the main body and the wearer's legs as disclosed, for example, in Published Japanese Translation of PCT International Application No. 2000-513636. Thereby, it is possible to fit the open-type diaper on the waistline of the wearer and to bring the diaper into close contact with the crotch of the wearer.
When the known disposable diaper is put on the wearer, an absorbent surface of the main body is firstly fitted to the crotch of the wearer. Subsequently, the waistline member is stretched so as to fit to the waistline of the wearer, and is then fastened to the main body with the fastening tapes.